1. Field of the Invention
Methods and apparatuses consistent with the exemplary embodiments relate to nitride semiconductor and a fabricating method thereof, and more particularly to GaN based compound semiconductor with a high concentration nano size fin shape without heterojunction, and a fabricating method thereof
2. Description of the Prior Art
In general, silicon (Si) and gallium arsenic (GaAs) is widely used in semiconductor for application to low power and low frequencies. However, due to a narrow bandgap and breakdown voltage, the aforementioned semiconductor material could not be used in high power high frequency application devices to a desired extent. For example, Si has a bandgap of 1.12 eV and 1.42 eV at room temperature.
Accordingly, in application devices and elements of high power, high temperature and high frequency, much interest was drawn to broad bandgap semiconductor material such as silicon carbide and group III nitride. For example, α-SiC has a bandgap of 2.996 eV, and GaN of group III nitride has a bandgap of 3.36 eV at room temperature. As such, material for silicon carbide and group III nitride have electric field breakdown strengths and electron saturation velocity higher than GaAs and Si.
An element which draws particular interest as a high power, high temperature and high frequency is high electron mobility transistor (HEMT) well known as modulation doped field effect transistor; MODFET. Such an element is formed by heterojunction of two semiconductor material having bandgap energy with different 2-Dimensional Electron Gas (2DEG-2), wherein since any material with better bandgap has higher electron affinity, it provides advantages in various environments. 2DEG is an undoped accumulation layer of narrow bandgap material, and includes a very high sheet electron concentration of approximately 1012 to 1013 carrier/cm2. In addition, electrons generated in doped broad bandgap semiconductor is transmitted to 2DEG, enabling high electron mobility by reduced ion impurity dispersion.
Meanwhile, a conventional HEMT element grows 2 layers such as AlGaN and GaN for example in order to perform heterojunction, wherein it is very difficult for AlGaN to grow.
In addition, in a case of using GaN as a power switch element, there needs to be a normally off characteristic, but due to heterojunction, it is always normally on, which is a problem.